Hybrid electric vehicles (or HEVs) utilize mechanical power from an internal combustion engine (or ICE) and electrical power from a battery pack. HEVs can alternatively rely on the ICE or battery pack for power; or the HEV can run off of a combination of the two. A generator is used to accumulate electrical power during ICE rotation. ICE utilization requires the use of several support systems that use electrical power including, for example, the fuel system. Powering the fuel system for any length of time when the engine is not being used by the powertrain consumes battery power unnecessarily.
Some conventional hybrid vehicles manage control of the fuel system according to the vehicle mode of operation. For example, U.S. Pat. No. 7,680,568 titled “Method of Controlling Engine Stop-Start Operation for Heavy-Duty Hybrid-Electric and Hybrid-Hydraulic Vehicles” discloses control of fuel injectors according to engine turn off or shutdown sequences. It is still desirable to have greater power conservation with respect to fuel pump utilization when the vehicle's powertrain is not relying on the ICE for power.
Other conventional systems turn off the fuel pump after the engine has completed a pull down cycle. However, even greater amounts of energy can be conserved prior to the end of an ICE pull down cycle.
Therefore, it is desirable to have a method for controlling a HEV fuel pump with improved efficiency.